Button-rifled, 4140 chrome moly or stainless steel barrel blanks are stress-relieved and air gauged to +/- .0002" for superb accuracy and performance from your custom rimfire rifle. Not chambered or threaded, ready for custom fitting. Mfg: Green Mountain SPECS: 4140 chrome moly steel (CM) or stainless steel (SS), in-the-white. 1.06" (27mm) O.D.; lengths listed in table below.